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The versatility of Go errors
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| // Note: This is _just_ an example of the versatility of Go, or, more specifically, first-class functions and duck-typing. | |
| package main | |
| import "log" | |
| type R string | |
| type E func() string | |
| // An example of a "catch" error function factory. | |
| var Failure = func(message string, callback func()) error { | |
| return E(func() string { | |
| log.Printf("%s failed. I can handle it here.", message) | |
| callback() | |
| return message | |
| }) | |
| } | |
| // This makes E an error. | |
| func (e E) Error() string { | |
| return e() | |
| } | |
| // A more simplistic way to handle errors. | |
| func catch(r R, err error) R { | |
| if err != nil { | |
| log.Println(err) | |
| } | |
| return r | |
| } | |
| // A similar simplistic way to make an error exceptional. | |
| func throw(r R, err error) R { | |
| if err != nil { | |
| panic(err) | |
| } | |
| return r | |
| } | |
| // | |
| func DoStuff() (R, error) { | |
| return "great", nil | |
| } | |
| // | |
| func FailThings() (R, error) { | |
| return "", Failure("FailThings", func() { | |
| log.Printf("handled") | |
| }) | |
| } | |
| // | |
| func main() { | |
| catch(DoStuff()) // No error. Nothing logged. | |
| throw(DoStuff()) // No error. Nothing thrown. | |
| catch(FailThings()) // Errors so catch prints the error which calls the callback. | |
| throw(FailThings()) // Errors so throw panics after the callback. | |
| } |
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